Multiswitches are used for distribution of satellite and terrestrial TV signals. The signals are distributed by separate paths right down to the end-of-line multiswitch, where they are combined and transmitted by one cable to the "destination" outlet.So the two kinds of signals are processed independently, by active satellite path and passive or active terrestrial path.

In the case of passive terrestrial path the signals are distributed via passive splitters, for active solution - additionally amplified to compensate loss.In the first case there are no limits for maximum input signal level, in the second - the maximum level is the indicator of multiswitch quality. It is 100 dBuV for Terra multiswitches and only 80 dBuV for Satmatrix or Viper products. The cheaper multiswitches cannot be used in locations with large differences in signal levels or in more extensive networks. Overdriving of such a multiswitch will result in low quality image of the strong channel and interferences on other channels.

There is big difference in attenuation between passive and active terrestrial path. The passive path of MS-952, MS-554 multiswitches decreases signal level by 19dB. The active path of MSR-9XX multiswitches attenuate terrestrial signals by 5 to 11 dB (in depends on the output).

The advantages of multiswitches from Terra also include possibility of control by ToneBurst signal and transparency for remote control extenders, e.g. Signal-Link R93109 (only MS series).

Multiswitches have to be selected according to the number of users (outlets), satellites, LNBs. Below we present a table and several diagrams which can help to choose appropriate solution. In these examples there are used well proved multiswitches from Terra.

Multiswitches from Terra - a basic comparison

Notice: It is possible to build larger installations (for a greater number of users/outlets), but the network has to be divided in sub-networks with satellite splitters (SS-504 R70515), or taps (SS-510 R70516, SS-515 R70517, SS-520 R70518).

Installations for reception from one satellite. This kind of installations allows cost reduction - it is the simplest solution. It is sufficient when all or the overwhelming majority of interesting programs are accessible from one satellite position.

Installation for receiving programs from one satellite, using both lower and upper bands, in a building with one trunk line

Analyzing a specific design we should find out whether satellite signal level decreases by more than 30dB, or the terrestrial TV signal level is lower than 62dB (any received channel). If so, some amplifiers have to be used:

Installation for reception of programs from one satellite with cascade of multiswitches, with use of amplifiers, designed for big apartment house

When in a building there are two or more trunk lines (e.g.two or more staircases), the division into sub-networks will improve general reliability of the system.

Notice: This concept is obligatory in installations for more than 40 users.

Installation for receiving programs from one satellite, using both lower and upper bands, in a building with two trunk lines (two staircases)

Installations for reception from two satellites. Nowadays it is probably the most common case, ensuring reception from the both most popular satellites in Europe: Astra and Hotbird. For one-family houses we propose the multiswitch MS-952, allowing independent use of four receivers.

Installation for receiving programs from two satellites in one-family house

In the pictures below we present analogical solutions for apartment houses, in versions with amplifiers and without them, depending on calculations of the result attenuation.

Installation for receiving programs from two satellites with cascade of multiswitches (in a small apartment house); it is also shown the possibility of connecting signal from head station

Installation for reception of programs from two satellites with cascade of multiswitches and amplifier, using division into sub-networks, for greater number of users (subscribers)

The tips for installers of Terra multiswitches

1. It is very important to equalize signal levels at different inputs. It especially concerns signals from both bands and from two different satellites. The adjustment of signals from two different polarizations is not so essential, as they differ in frequency and do not interfere much. If the signal levels differ a lot, in the case of 9-input multiswitches, the "stronger" satellite should be connected to input A, and the "weaker" to input B, according to the marks on the housing.

2. The level of satellite signals should be between 50-90 dBuV. The upper limit is a result of the maximum output level 102dBuV. It is well to remember that the MS951and MS553 multiswitches are characterized by certain pass-through loss, yet not big - 2.5dB. It means that the number of cascaded multiswitches should not exceed 3 - 4, unless satellite amplifiers are to be anticipated.

3. The level of terrestrial TV signals on the input of the multiswitch should be between 80-95 dBuV. So high value arises from the employed passive path. The attenuation between terrestrial input and output to a receiver is (for all multiswitches) about 19 dB, and their pass-through loss - about 3.5 dB.

4. Terrestrial TV signals are available even when no SAT receivers are connected and multiswitches are not powered at all.

5. Each unused input has to be closed with 75 oh terminating resistor. The resistors connected to satellite inputs and outputs cannot pass DC. The outputs to receivers can be left unloaded.

6. When using 18 V power supply for MS952 multiswitches, at the inputs associated with vertical polarization there is available 14 V, whereas at inputs associated with horizontal polarization it is 18 V. Loss of supplying voltage on pass-through multiswitches is not higher than 0.1 V, on the assumption that the LNBs' current is lower than 1 A.

7. 9-input multiswitches are prepared for control with DiSEqC 2.0 signals and the standard signals: 14/18 V voltage, 0/22kHz tone, Tone Burst. After being switched on, the multiswitch waits for DiSEqC commands, and only when they do not occur it reacts to the standard signals.

In the case when old receivers are not compatible with DiSEqC or Tone Burst standards, only satellite A is available. The access to B satellite is exercised with "Position A/B - Hi/Lo Band" switches. These switches change 22 kHz function from band change to satellite change. The upper band for A/B positions is not achievable then.